This application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2010-108532 filed in Japan on May 10, 2010, the entire contents of which are herein incorporated by reference.
The present invention relates to an image forming apparatus provided with a resin frame made of resin, image forming units and a fixing unit.
A frame that constitutes the basic structure of an image forming apparatus such as a copying machine, a printer, a facsimile machine or a digital multifunction machine is conventionally a metal frame structure made by assembling conventional pressed metal parts or metal based steel materials by joining or welding.
In a recent trend of reducing the production cost of image forming apparatuses, conventional metal frames are not sufficiently profitable. Moreover, there is a great demand for compactness and lightness of weight, which requires simplicity of structures and reduction of the number of parts. Considering these circumstances, there is a limit in compactness and lightness of metal frame structures.
Resin frames made of resin may be adopted in view of cost reduction, compactness and lightness of weight required for frame structures, but in this case there may be problems as follows.
A complicated die for molding a resin frame is needed when producing resin frames. In particular, when a frame for an image forming apparatus compatible with a large image formation size of A3 or larger is required to be produced with resin, a large die is needed, which increases die preparation time, die cost and so on.
For an image forming apparatus provided with a fixing unit and image forming units (process units) including a photosensitive unit, a charging unit and a development unit, a structure for suppressing heat transmission from the fixing unit to the image forming unit has been proposed.
For example, JP H10-143053A (Patent Document 1) and JP H9-222760A (Patent Document 2) disclose image forming apparatuses provided with a duct in a space between the image forming unit and the fixing unit.
However, in the image forming apparatuses disclosed in Patent Documents 1 and 2, heat transmission from the fixing unit to the image forming unit can be suppressed, but there is no consideration to the problem of the necessity of a complicated die for resin frame molding that is compatible with a large resin frame.
Therefore, it is an object of the present invention to provide an image forming apparatus provided with a resin frame made of resin, an image forming unit and a fixing unit that can suppress heat transmission from the fixing unit to the image forming unit while simplifying a die for molding the resin frame.